The Gene Silencing Section, (GSS) Genetics Branch, aims to be a group with specific expertise within CCR for the study and application of RNAi in mammalian cells. The scientific and clinical developments in the field of RNAi are rapidly impacting our understanding of the role of RNA silencing mechanisms on the control of normal and disease related gene expression, including cancer. Further, technological developments utilizing the RNAi mechanism have been developed for the analysis of gene function and the development of new model systems. More recently RNAi based analysis has been used for improved understanding of drug: target interactions and target identification, and these strategies are now being scaled to enable large scale screening, potentially up to whole genome. In addition to our project based research (see other project reports) we have played an extensive role in assisting and training CCR investigators in the use of RNAi for gene function analysis including, though not limited to, the training of Investigators and Post Doctoral Fellows in different aspects of RNAi analysis technologies, the sharing of protocols and RNAi characterization data (see below), as well as direct collaboration. To develop our first large scale RNAi effector resource Dr. Caplen, the GSS section head, has pursued a research collaboration agreement (RCA #2-18668-05, AKA MTA 18668) between the Gene Silencing Section, Genetics Branch, CCR and Qiagen Inc that was renewed in 2007 for a further three years. We are also increasingly focusing our efforts on the use of RNAi screening approaches and a number of independent and collaborative RNAi screens have been initiated.